1. Field of the Invention
The present invention relates to a winding mechanism and, more particularly, to an auto winding mechanism for a window blind.
2. Description of the Related Art
A conventional auto winding mechanism for a window blind in accordance with the prior art shown in FIGS. 1 and 2 comprises an upper seat 40, a lower seat 41 connected with the upper seat 40, two guide rollers 45 pivotally mounted between the upper seat 40 and the lower seat 41, and two pull cords 44 wound around the two guide rollers 45 in two opposite directions. The two guide rollers 45 are connected by a S-shaped elastic winding tape 42. Each of the two guide rollers 45 has an upper end connected with the elastic winding tape 42 and a lower end connected with a respective one of the two pull cords 44. Each of the two guide rollers 45 has a periphery provided with a gear 43, and the gears 43 of the two guide rollers 45 mesh with each other so that the two guide rollers 45 are rotated in concert with each other.
When in use, the auto winding mechanism is mounted on a window blind. The window blind includes a headrail, and a plurality of shading members. The auto winding mechanism is mounted in the headrail of the window blind, and the two pull cords 44 are in turn extended through two opposite ends of each of the shading members to connect and draw the shading members. The elastic winding tape 42 provides an elastic force to support the weight of the shading members to reach a balance state. When the shading members are pulled by a user, the two pull cords 44 are pulled outward and downward to drive and rotate the two guide rollers 45 and to stretch the elastic winding tape 42 so as to store a restoring force. Thus, the user can directly pull and draw the shading members to lift or lower the shading members and to stop the shading members at any position.
However, when the pull cords 44 are moved rapidly, the pull cords 44 will easily swing upward and downward or bump so that the pull cords 44 are easily clamped or jammed between the lower seat 41 and the guide rollers 45, thereby causing the auto winding mechanism to be inoperative.